Rationale, Technique, and Results of the
DJO Surgical Reverse Total Shoulder Arthroplasty
Matthew Walker, MD,* Derek Pupello, MBA,
and Mark Frankle, MD*
Reverse shoulder arthroplasty for the treatment of rotator cuff-deﬁcient shoulders has
improved patient outcomes compared with previous treatment options. Improvements in
prosthetic design have resulted from parallel biomechanical and clinical research efforts
that have provided an evidence-based foundation. Improving component ﬁxation and po-
sitioning, providing differing prosthetic sizes and geometries, and maintaining normal
humeral neck shaft angle and retroversion have allowed a decrease in prosthetic-related
complications, such as mechanical failure, impingement, and instability while allowing
consistent improvements in shoulder function. Clinical and biomechanical research will be
discussed which has provided the design rationale for the Reverse Shoulder Prosthesis
(DJO Surgical, Austin, TX), formerly known as the Encore Reverse Shoulder Prosthesis.
Speciﬁcally, we will focus on: (1) baseplate ﬁxation with a central ﬁxed lag screw and
peripheral locked screws, (2) tilting the glenoid component, (3) glenospheres with center of
rotation close to anatomic (lateral to the surface of the glenoid), and (4) humeral component
with an anatomic neck shaft angle.
Oper Tech Orthop 21:60-68 © 2011 Elsevier Inc. All rights reserved.
KEYWORDS biomechanics, encore, reverse shoulder arthroplasty
everse total shoulder arthroplasty (RTSA) was developed
to address the need for a treatment with better clinical
outcomes and more predictable functional results in patients
with rotator cuff deﬁcient shoulders and glenohumeral ar-
thritis. In these cases, anatomic, constrained shoulder re-
placements were inadequate in restoring stability and with-
standing the forces in the glenohumeral joint and, hence,
were later abandoned (Fig. 1).
The initial RTSA designs
from the 1970s were largely experimental, with outcomes
data consisting of relatively small patient cohorts (Fig. 2).
Furthermore, these early series noted complication rates be-
However, in reporting the failures of
the devices from the 1970s, the greater complication rates of
the constrained anatomic devices (up to 100%)
grouped together with the lower complication rates of the
Boileau et al
summarized the ﬁndings of
2 reports on the Kessel prosthesis as examples of the high
complication rate of the constrained RTSAs that led to their
removal from the market and the impetus for the Grammont
design. These 2 studies reported different complication rates
for the Kessel design; one noted a 16% complication rate,
whereas the other noted a complication rate of 26%.
effort to understand failures in these earlier series, Boileau et
suggested that those RTSAs tended to fail because their
design resulted in excessive torque and shear forces at the
glenoid baseplate-bone junction. However, alternative expla-
nations for prosthetic failure should also be considered, such
as increased constraint, inadequate glenoid ﬁxation, lack of
bone in-growth material properties, and patient selection fac-
tors. Because early reports noted clinical success with the use
the Grammont prosthesis, theories were put forth to provide
a rationale as to why the complication rates were lower than
the original RTSA designs. Interestingly, when reviewing the
published series in complication rates, the Grammont design
had complication rates up to 60%.
In addition, in a study by
Werner et al (2005),
the reoperation rate of the Grammont
design was 33%— greater than that of several series of origi-
nal RTSA designs.
Despite high complication rates noted in some series’ with
the Grammont design, the clinical results have been promis-
This ﬁnding is encouraging because cuff tear
arthropathy represents a problem that previously had no so-
lution. However, implant features central to the Grammont
*Florida Orthopaedic Institute, Tampa, FL.
†Foundation for Orthopaedic Research and Education, Tampa, FL.
Dr Frankle receives royalties from DJO surgical and is a designing consultant
for DJO surgical.
Address reprint requests to Mark Frankle, MD, 13020 Telecom Pkwy N,
Tampa, FL 33637. E-mail: email@example.com
1048-6666/11/$-see front matter © 2011 Elsevier Inc. All rights reserved.